6 to 10 feet deep at the centerc. It might be made of concrete^ with an 

 inner face of glazed tilec Circulation and exchange of water might be 

 effected by pumps of large capacity j with the inlet directed along the 

 inside wall to produce a circular currento If the tank were located 

 inshore, say on a coral reef, circulation might be accomplished by means 

 of a propeller or paddle wheel installed in the screened opening,, the 

 sides of which would be tangential to the wallo A very strong current, 

 which would promote rapid swimming and thus produce a large flow of 

 water over the gills of the fish, may be necessary for the survival of 

 fast swimmers such as the skipjack and frigate mackerels It has been 

 amply demonstrated that rapid swimming is not necessary for the survival 

 of small tunny and yellowfino However^ with an arrangement such as that 

 just described^ it might be possible to arrive at an optimum current 

 flow and thus an optimum swimming rate which might decrease mortality^ 

 particularly during the period of adjustment in the latter specieso 



No references to the establishment of tuna in captivity have 

 been encountered in the literature^ although it has been done in Japan 

 and perhaps elsewhereo During a recent (1951) trip to Japan, Professor 

 Iwao Miyake, University of Hawaii ^ reports having seen about 100 meji 

 maguro (small black tuna^ Thunnus orientalis ) living in an inshore 

 enclosure made of webbings The enclosure,, which was about 90 feet long, 

 30 feet wide, and from 3 to 15 feet deepf, was located at Mitohama, near 

 Shizuokar, Other visitors to Japan have reported seeing tuna confined 

 in a circular tankc 



The present work^ while only moderately successful p has 

 demonstrated the feasibility of holding two species of tuna in con- 

 finement for an extended period of timoj, thus providing material for 

 studies of their behavior ,, feeding„ food consumptionp growth^ and reac- 

 tion to stimuli under experimental conditions,, It has also indicated 

 ways in which the methods of catching, handlings transportation, and 

 retention might be improved for greater survivalo 



ACKNOWLEDGMENTS 



'« 



Much credit for success must be given to Mto Lester Zukeran, 

 skipper of the Salpa. , who conducted the fishing expeditions with great 

 skill and patience, and who aided in the handling and transfer of the 

 fisho Credit must also be given to Mto Charles Nakamoto for assistance 

 in fishing, and especially for the care and feeding of the fish in cap- 

 tivityo To these employees of the Hawaii Marine Laboratoryp and to 

 members of the staff of both the University of Hawaii and the Pacific 

 Oceanic Fishery Investigations who assisted occasionally in fishing, 

 I wish to express my sincere thankso 



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